Loud-speaker



June 10, 1930. c; HQPKINS 7 1,763,055

LOUD SPEAKER Filed Jan. 7, 1927 2i 1 V I j 'INVENT 1 I f/arca; ."f/o a .s,

ATTORNEY-5 Itatented June 10, 1930 UNITED- STATES PATENT, OFFICE j E0115 0. 'HOPKINS, OF'WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR TO TITANA- FRAM COBPOKATION, OF JERSEY CITY, NEW JERSEY, A CORPORATION OF DELA- WARE LOUD-SPEAKER Application filed January 7, 1927. Serial No. 159,555.

The present invention relates to a loud speaker suitable for use with radio-receiving sets or as announcers for telephone and like wired circuits, which will reproduce the sound waves without the distortion of a horn or other amplifying device, the sound sorewas derived.

The loud s aker of this invention, like the loud-sp'ea er described in my co nding application Serial No. 77,033, filed ee. 22, 1925, comprises a central relatively light and stifi diaphragm or tympanum preferably conical in shape, and a surrounding external sound boardor resonator. In such loud speakers the central diaphragm responds to t e relatively highfrequencies and will effectively'reproduce thehigh tones or sounds, and the relatively low frequencies will be transmitted to the sound board so that it will respond to the relatively low frequencies and will effectively reproduce them.

It is desirable that the soundin board or resonator have an area substantia ly greater than the area of the central diaphragm, and

the principal object of the present invention is to provide a loud speaker having a sounding board of ample area without unduly increasing the size of the speaker. To this end, I have provided a supplemental sounding boardhaving a periphery substantially coextensive with the periphery of the main sounding board, and have mounted it so that .hit extends substantially parallel with said main sounding board and is connected thereto at intervals adjacent its outer periphery to the outer periphery of the main board. By thus connecting the outer edges of the two sounding boards together, the vibrations from the diaphragm will be imparted to the sounding board surrounding it, which, in turn, will transmit the vibrations when they reach its outer ed e, to the'second or supplemental sounding board.

If the sound waves are to be reproduced clearly and without distortion, it is essen-' tial that the supplemental sounding board shall not interfere. with the sound coming from the central diaphragm and the sounding board. In order to obstruct the sound waves emanating from the sound board and from the diaphragm as little as possible, the supplemental diaphragm is provided with relatively large apertures through which the sound may readily pass.

A further object of the invention is to provide a sounding board which will reproduce the relatively low frequencies as effectively as possible, and to this end, the invention comprises the use of corrugated board for the formation of the sounding boards.

The preferred form of my invention is illustrated in the appendeddrawings, in which Figure 1 is a front view of the loud speaker embodying my invention;

Fig. 2 is a side view of the same;

Fig. 3 is a central sectional view taken through the loud speakeron line 33 of Fig. 1; and

Fig. 4 isa detail sectional view of the sounding board.

In the drawing, the numeral 1 designates the central diaphragm or tympanum which is preferably of conical shape and actuated in the usual manner by an electrical actuating mechanism 2. While the electrical actuating mechanism may be of any desired construction, I prefer to use an electrical movement such as is shown and described in an application I have filed concurrently herewith. Surrounding the diaphragm l is a sounding board 3 which, according'to the present invention is made of corrugated qualities of the speaker due to a decrease in the size of the sounding board, I have provided a supplemental sounding board or resonator 6, which is preferably arranged in front of the diaphragml and the sounding board 3, and which is spaced parallel therefrom. This supplemental sounding board, like the main sounding board which surrounds the central diaphragm, is made of corrugated board so that the sounds which it reproduces will be clear in tone and not distorted.

In order that the supplemental sounding board may receive the vibrations from the main sounding board I have provided suit-I able connecting members 7 for connecting the outer edges of the two sounding boards together. These connections preferably comprise connecting posts which are arranged at intervals around the periphery of the speaker. By thus arranging the connecting members 7 at intervals, the sound waves which emanate from the main sounding board and from the diaphragm are allowed to pass out between the two sounding boards. It is also necessary that the sound Waves which emanate from the sounding board and the diaphragm shall be permitted to pass straight out without material interference. In order that this may be accomplished, I have provided the supplemental sounding board with a plurality of relatively large apertures 8 arranged over substantially the entire surface of the sounding board. These relatively large apertures allow the sound waves to pass through the supplemental sounding board with a minimum of interference and without distortion. 7

It will thus be seen that I have provided a loud speaker which has a sounding board of ample size with respect to the diaphragm without materially increasing the size of the speaker as a whole, and that the vibrations which are transmittedfrom the central diaphragm to the main sounding board, will, when they reach its outer edge be transmitted through the connecting members 7 to the supplemental sounding board 6, which will effectively aid the main sounding board inreproducing the relatively low frequencies without in any way affecting or materially interfering with the sound waves emanatin from the main sounding board and the dia phragm.

As the central diaphragm is located bebrations from the diaphragm to one of the resonators and means for transferring vibrations'from one of the resonators to the other. 2. A loud speaker compr sing a diaphragm,

' a plurality of spaced parallel resonators made of corrugated board, one of said resonators having a plurality of openings therein, means 4 for transferring vibrations from the diaphragm to one of the resonators and means for transferring vibrations from one of the resonators to the other.

3. A loudspeaker comprising a diaphragm, a sounding board, a connection between the edge of the diaphragm and the sounding board having flexibility suflicient to permit the diaphragm -to respond to relatively high frequencies and having stiffness sufficient to transmit the relatively low frequencies to the sounding board, a supplemental sounding board and means for transferring vibrations from the first sounding board to the supplemental sounding board.

4. A loudspeaker in accordance with claim 3 in which the supplemental sounding board is parallel to the first sounding board.

5. A loudspeaker comprising a conical dia phragm, a sounding board, a connection between the edge of the conical diaphragm and the sounding board having flexibility suflicient to permit the conical diaphragm to respond to relatively high frequencies and having stiffness sufiicient to transmit the relatively low frequencies to the sounding board, a supplemental sounding board and means for transferring vibrations from the first sounding board to the supplemental sounding board.

6. A loudspeaker in accordance with claim 3 in which the supplemental sounding board is parallel to the first sounding board and wherein the means for transferring vibrations from the first sounding board to the supplemental sounding board are arranged adjacent MARCUS C. HOPKINS. 

